Hydraulic thrust mechanism for power shovels



Jan. 15, 1935. w. FERRIS 1,937,613

HYDRAULIC THRUST MECHANISM FOR POWER SHOVELS Filed March 17, 1933 2 Sheets-Sheet 1 AV A 3mm WALTER FERRIS.

Jan. 15, 1935. w. FERRIS 1,987,613

HYDRAULIC THRUST MECHANISM FOR POWER SHOVELS Filed'March 1'7, 1933 2 sheets-she 2 INVENTOR; WALTER FERRIS. BY WM4Y I 1 9W ATTORNEXS.

Patented Jan. 15, 1935 HYDRAULIC THRUST MECHANISM FOR POWER SHOVELS fwauer Ferris, Milwaukee, Wis., assignor to Bucyrus-Erle Company,

South Milwaukee,

Wis., a corporation of Delaware Application March 17, 1933, Serial No. 661,247

14 Claims.

This invention relates to'power excavators, and particularly to power shovels, and more particularly to hydraulic mechanisms for one of the auxiliary motions thereof, and still more particularly to hydraulic thrust mechanisms.

. tions the reaction is negative.

The power excavator to which the invention applies inparticular is of a type wherein the dipper or shovel is carried by a dipper stick mounted to hoist in a vertical are about a fixed point on the boom, and also to shift lengthwise with respect to this point. The hoisting action is effected through a hoist cable, ordinarily connected to the dipper, and usually directly actuated by an engine of some sort, mounted on the main frame of the excavator. This hoisting motion is the main motion of this type of excavator. The lengthwise shifting motion of the dipper stick is one of the auxiliary motions, and is effected by an independently controlled thrust mechanism, ordinarily geared to the dipper stick. Other auxiliary motions include swinging the entire main frame about a vertical pintle, raising and lowering the boom, etc.

The load and reaction on the thrust mechanism varies widely in the various positions of the dip er; In fact in some positions the reaction-onthe thrust mechanism is positive while in other posie.

One object of the present invention is theprovision of 'an improved hydraulic meansiorftha eflicient operation and control of the dipper? mechanism, or any other of the auxiliaries:

Another object is the provision of a hydraulically actuated thrust mechanism which will afford positive control of the thrusting action, or other auxiliary, without requiring the use of power wasting throttle valves, brakes, or clutches, such as heretofore employed in fluid actuated or mechanically driven shovels.

Another object is the provision of a hydraulically actuated thrust mechanism, or other auxiliary, which can be released, at the will of the operator, to permit, for example, the dipper stick J to shift freely as desired in the various angular $118.1 manner.

swing about the axis of this shaft in the custom-j ,ary manner. The stick 15 is equipped with the adjacent the base of the boom 11 and connected Fig. 2 is a detail of the pump control mechanism shown in Fig. 1. Fig. 3 is a longitudinal sectional view of a by-.

- pass valve shown in Fig. 1.

Fig. 4 is a sectional view of the valve taken on 5 the line 4-4 of Fig. 4. I

Fig. 5 is a diagrammatic illustration of a modifled form of hydraulic transmission embodying the present invention and including a singlelever control for the thrust mechanism.

Fig. 6 is a view similar to Fig. 5 illustrating a further modification including a variation of the single=lever control system of Fig. 5.

' The power shovel shown in Fig. 1 includes a conventional platform 10, carrying a boom 11 and rotatably mounted upon the truck frame 12, so as to swing about a vertical axis in the The dipper 13, operated by the hoist cable 14, is secured in a conventional manner to the end of the stick 15 so as to swing therewith about the shipper' shaft 16 and so as to respond to longitudinal movements of the stick in' the saddle block 17. The shipper shaft 16 is journalled in an appropriate bracket 18 on the boom 11, and the saddleblock is mounted to usuafrack 19 geared to a pinion (not shown). on the shaft 16 through which the stick is longi tudinally'actuated by rotation of the shaft.

In this instance the shipper shaft 16 is actuated. and controlled by an improved thrust mech- Such as will now be described. This mechanis'mjcomprises a rotary hydraulic motor M of a well known type, carried by the platform 10 in driving relation with the shipper shaft 16 through appropriate means such as a sprocket and chain connection 20. Although the motor shown is of a type such as that described as a part of the hydraulic transmission disclosed in my prior Patent No. 1,628,603, issued May 10,. 1927, the use of that particular type of motor is not essential to the present invention.

The motor M is included in a closed hydraulic circuit comprising the pipes 21 and 22 which are connected thereto and to a variable displacement, reversible flow pump P of any known or approved type. The pump shown is fully described in my prior Patent No. 1,558,002, issued October 20, 1925. Or, instead of a reversible pump, it may be desired to use an irreversible, variable displacement pump, with a reversing valve to reverse the flow in the motor, M. Such a pump is fully described in my prior Patent No. 5

1,798,198, issued March 31, 1931. In this latter alternative, it is not necessary that the hydraulic circuit be a closed one. The circuit; might, in that case, be provided with an open oil-pot, from which the pump draws oil, and into which the oil from the motor drains. The reversing valve necessary in this case may be incorporated with the by-pass valve later to be described, since it may be governedby the bypass valve hand lever.

As a reversible variable displacement pump and an irreversible variable displacement pump plus a reversing 'valve are equivalent, they will be interchangeably referred to herein as a reversible variable displacement pump.

The pump is normally driven at constant speed by a suitable motor (not shown), preferably the same motor which actuates directly'the main hoist motion of the shovel. This pump is provided with displacement regulating means by which the rate and direction of discharge therefrom may be manually varied at the will of the operative. The displacement regulating means is controlled by a longitudinally movable stem 23 which in this instance is geared to a pinion 24 actuated and controlled by a hand lever 25, as indicated particularly in Fig. 2.

The arrangement is such that when the hand lever 25 is in intermediate position 2, pump displacement is zero, the liquid in pipes 21 and 22 is at rest, and the motor 17 is thereby held against rotation. When the hand lever is moved toward position 1, the pump discharges through pipe 21, at a rate corresponding to the extent of such movement, thereby driving the motor at a corresponding rate and in such direction as to thrust the stick 16 and dipper 13 outwardly. During actuation of the motor in the direction last named the liquid discharged therefrom returns to the pump through the pipe 22. When the hand lever is moved from position 2 to position 3, the pump discharges through pipe 22, at a rate correspondingto the extent of such movement, thereby driving the motor at a corresponding rate and in the opposite direction, so as to retract the stick and dipper.

It will be observed that when the dipper and stick are in the full line position of Fig. 1, the tension in the hoist cable 14, together with the weight of the dipper and its load, urges the stick inwardly; whereas when the dipper and stick are in the dotted line position shown, the weight thereof together with the tension in the cable 'tends to urge the stick outwardly. The reaction of the stick upon the shipper shaft 16 thus varies considerably in the various positions of the dipper, s'ometimes tending to rotate the shaft in one direction and sometimes. in the opposite direction. Nevertheless the hydraulic system, including the closed hydraulic circuit above described, provides a positive control for the shipper shaft regardless of the nature of the reaction imposed thereon by the stick in the various positions of the dipper.

In some instances, however, it is desirable to release the shipper shaft so as to permit the stick 15 to run freely in the block 1'7, as, for example, when the operator wishes to drop the dipper rapidly into digging position. In the shovel shown, this is made possible by the use of an appropriate by-pass valve 26, connected through pipes 27 and 28 with the two sides of the hydraulic circuit- A valve for this purpose, shown in detail Figs. 3 and 4, includes a longitudinally movab plunger 29 having an intermediate reduced portion 30 and a head 31 which controls communication between two annular chambers 32 and 33 formed in the valve block. Pipe 27, connected with circuit pipe 21, communicates with chamber 32, and pipe 28, connected with circuit pipe 22, communicates with chamber 33.

With the plunger in the position shown in Figs. 3 and 4, communication between chambers 32 and 33 is blocked by the head 31 and the circuit functions in the manner hereinabove described; but when the plunger 29 is shifted toward the right, so as to connect chambers 32 and 33, the circuit is by-passed through the pipes 2'7 and 28 and valve, and the motor is then free to idle with the shipper shaft 16. The valve is controlled in this instance by a hand lever 34.

This by-pass arrangement may also be used to advantage when it is desired to forcibly shake the dipper tocompletely free it of its load when in elevated position for dumping. When, for instance, the dipper is in the upper position of Fig. 1 with the pump set to advance the stick 15, the valve 26 may be operated to repeatedly open and close the by-pass connection, thereby alternately to advance the stick by the action of the pump when the by-pass is closed and to retract the stick by the weight of the dipper and the tension in the hoist cable when the by-pass is open.

In order to protect the circuit against excessive pressure a high pressure relief valve 35 of a well known type is connected across the circuit in such manner that, whenever the pressure in either side thereof exceeds a predetermined maximum, liquid may escape therefrom to the other side of the circuit.

Each of the modified embodiments of the invention shown in Figs. 5 and 6 includes the motor M and the variable displacement, reversible flow pump P, connected by the closed hydraulic circuit including pipes 21- and 22, in the same manner as in the hydraulic system hereinabove .described. A similar by-pass valve 26 is-emlever 40 is mounted to swing about the center 41 I and two cam plates 42 and 43 are connected to swing therewith. In Fig. 5 the plate 42 is provided with a cam slot 44 in which a lateral projection 45 On the end of the pump control stem 23 is engaged; and plate 43 is provided with a cam slot 46 in which a lateral projection 4'? on the valve operating stem 48 is engaged.

The slot 44 is so shaped that with the hand lever 40 in the intermediate position 0 pump displacement is zero and the motor and connected parts are held stationary; as the lever is moved in one direction toward position 1, pump displacement is increased causing the motor to operate at an increasing speed in such direction as to thrust the dipper forwardly; when the lever reaches position 1, pump displacement is at a maximum and continues so in all positions beyond position 1; as the lever is moved from position ,0 toward position 1, pump displacement is again increased from zero, causing the motor to operate in the opposite direction to retract the dipper; and in all positions of the lever at and.

the hand lever between positions 1 and 1'. There-.

fore in all positions of the lever between position and one of the positions 1 or '1, the motor is actuated by the pump in a direction and at a rate dependent upon the direction and extent of lever movement from position 0.

The ends' of the slot 46 are so shaped that, as the lever 40 is moved beyond either of the positions 1 or 1',-the valve 26' is shifted to by-pass the circuit and thereby release the motor.

The effects produced by the several positions of the lever 40 (Fig. 5) may be briefly summarized by describing those effects in sequence as the lever is moved from position 2 to position 2'.

In position 2 the valve 26' is in by-pass position and the motor is free to idle with the shipper shaft; this condition maintains until the lever reaches position 1 in which position the motor is driven by the pump at maximum speed in such direction as to advance the dipper; by movement of the lever toward position 0, the speed of the motor is reduced until when the lever reaches position 0 the motor is held at rest; the motor is again actuated at gradually increased speed but in such direction as to retract the dipper as the lever is moved toward position 1'; and movement of the lever beyond position 1' again opens the by-pass to again release the motor. Provision is preferably made for resisting move ment of the lever beyond the positions 1 or 1' to thereby prevent accidental by-passing of the circuit and consequent release of the-motor. The means shown for this purpose comprise a pair of springs 4949' carried by the lever and disposed to engage one of a pair of fixed stops 50' or 50' whenever the lever is shifted into position In Fig. 6 the plate 43 is provided with a cam slot 46' so shaped that the valve 26' is in by-pass position when the lever 40 is in position 0, and so that the valve is immediately shifted to close the by-pass upon initial movement of the lever toward either position 1 or 1'; and so that the bypass remains closed in all other positions of the lever. Therefore, with the lever in position 0 the motor is free to idle with the shipper shaft, and in all positions beyond said initial range of movement the motor responds to the condition of the pump.

In Fig. 6 the slot 44' in plate 42 is so shaped that pump displacement remains zero in all. positions of the lever 40 between positions 1 and 1', so that in each position of the lever between the intermediate by-pass position and one of the positions 1 or 1' the motor and connected parts are held against operation; and as the lever is shifted beyond position 1 or 1' pump displacsment is increased so as to operate the motor in .one direction or the other at a rate dependent upon the extent of movement of the lever beyond position 1 or 1".

The eflects produced by the several'positions of the lever 40 (Fig. 6) may be briefly summarized by describing those effects in sequence as the lever is moved from position 2 to position 2'.

In position 2 the by-pass valve 26' is closed and the motor is driven by the pump at maximum speed in such direction as to advance the dipper; by movement of the lever toward position 1 the speed .of the motor is reduced, the motor being held against actuation when position 1 is reached; this condition maintains until the lever approaches position 0 and opens the by-pass valve to thereby release the motor and permit the same to idle with the shipper shaft; movement beyond position 0 again closes the by-pass so as to again hold the motor at rest until the lever passes beyond position 1'; and as the lever passes from'l' to 2' the motor is again actuated by the pump at an increasing rate, but in such direction as to retract the dipper, retraction at a maximum rate occurring when the lever reaches position 2'.

In the claims, the word uncushionedis intended to mean that the direct action of an incompressible fluid directly conveys the pressure of the pump to the motor, substantially the same as though the fluid were a rigid element. There is a fundamental distinction between the transthough the action in such a case ceases upon closing the admission valve, nevertheless, due to the pressure-head, exact control of the expansive effect of the pressure-head upon the motor is not possible during the time that the admission valve is open. It is only in the case ofan incompressible fluid without pressure-head that positive control is possible. Such control is peculiarly adapted to the solution of the problem solved by the present invention.

Various changes may be made in any of the embodiments of the invention hereinabove spzciflcally described without departing from or sacrificing the advantages of the invention as defined in the appended claims.

It should be evidentthat the hydraulic operating system, described and shown herein, is adapted to operate and control other auxiliary 'motions of the shovel, or the auxiliary motions of other types of excavators, or even the main motion thereof; although particularly advantageous in connection with the thrust motion, for

which it was primarily designed.

valve means for rendering said circuit inetlec-' tive, thereby r;leasing said motor from said locking action.

2. In a power shovel having a dipper and dipper stick, a hydraulic thrust mechanism therefor,

comprising the combination of: a constant displacement hydraulic motor operatively connected stick; a hydraulic thrust mechanism therefor,-

comprising: a hydraulic motor operatively connected with saidstick; a hydraulic pump; means forming a hydraulic circuit connecting said pump and motor, and normally effective to actuate and to positively control said motor in all positions of said stick, said means comprising a pair of passageways respectively effective to conduct liquid to said motor from said pump and from said motor to said pump; and means for rendering said circuit ineffective, thereby releasing said motor.

4. In a power shovel, the combination of: a dipper and dipper stick; a thrust mechanism therefor; and a hoist cable coacting with said stick to impose a variable reaction on said thrust mechanism in the various positions of said stick; said thrust mechanism comprising: a hydraulic motor operatively connected with said stick; a hydraulic pump; and means forming a hydraulic circuit connecting said pump and motor, and normally eifective to actuate: and to positively control said motor in all positions of said stick, said means comprising a pair of uncushioned passageways respectively effective to conduct liquid directly from said pump to said motor and from said motor to said pump.

5. In a power shovel, having a dipper and dipper stick, a hydraulic thrust mechanism therefor comprising: a constant displacement hydraulic motor; a variable displacement hydraulic pump; meansforming a hydraulic circuit between said pump and motor; valve means operable to bycomprising: a constant displacement hydraulic.

motor; a variable-displacement hydraulic pump; means forming a hydraulic connectionthrough which said motor is driven by said pump; a control element; means, controlled by said element, for regulating pump displacement to thereby regulate the rate of operation of said motor; and valve means controlled by said element for controlling said hydraulic connection.

7. In a power excavator, a hydraulic operating system comprising: a constant displacement hydraulic motor; a variable-displacement hydraulic pump; means forming a hydraulic circuit through which said motor is driven by said pump; a control element; means, controlled by said element, for regulating pump displacement to thereby regulate the rate-of operation of said motor or to lock said motor against rotation; and means, con- 'trolled by said element, for by-passing said circuit by said pump; a control element; means, controlled by said element, for regulating pump displacement to thereby regulate the rate of operation of said motor; and means, controlled by said element, for rendering said pump ineffective on said motor; said element comprising: a rockable member coacting with said two last named means to hold said motor against operation when said member is in intermediate position, to effect operation of said motor at an increased rate in either direction as said member is moved in either direction from said intermediate position, and to free said motor by extended movement of said member in either of said directions.

9. In a power excavator, a hydraulic operating system comprising: a hydraulic motor; a pump for operating the same at various speeds and in either of two directions; a control element; means, controlled by said element, effective to prevent operation of said motor when said element is in one position and to effect operation of said motor at various controlled speeds in either direction when said element is in other positions; and means, controlled by said element,.eifective to release said motor when said element is in a position other than those named.

10. In a power excavator, a hydraulic operating system comprising: a hydraulic motor; a pump for operating the same at various speeds and in either of two. directions; a control element; means, con trolled by said element, effective to prevent operation of said motor when said element is in one position and to efiectoperation of said motor at various controlled speeds in either direction when said element is in other positions; means, controlled by said element, effective to release said motor when said element is in a position other than-those named; and means for yieldably resisting movement of said element into motorreleasing position.

11. In a power excavatoiga hydraulic operating system comprising: a hydraulic motor; a pump for operating the same at various speeds and in either of two directions; a control element; means, controlled by said element, efiective in either of two positions thereof to hold said motor against operation, and to effect operation of said motor at various controlled speeds in either of two directions upon movement of said element beyond said positions; and means, operable in response to movement of said element into a position intermediate said first named positions, to release said motor.

12. In a power excavator, having a main motion and a plurality of auxiliary motions, a hydraulic mechanism therefor, comprising the combination of: a constant displacement hydraulic motor operatively connected with one of said auxiliary motions; a reversible variable-displacement hydraulic pump; means forming a closed hydraulic circuit connecting said pump and motor, and normally effective to actuate and to positively control said motor or to lock said motor against rotation in all positions of the hereinbefore mentioned auxiliary motion; means for regulating pump displacement, to regulate the speed and direction of operation of said motor; and valve means for rendering said circuit ineffective, thereby releasing said motor from said locking action.

13. In a power excavator, having a main motion and a plurality 'of auxiliary motions, a hydraulic mechanism therefor, comprising the combination of: a constant displacement hydraulic motor operatively connected with one of said auxiliary motions; a variable-displacement hydraulic pump, means forming a closed hydraulic circuit connecting said pump and motor, and normally effective to actuate and to positively control said motor or to lock said motor against rotation in all positions oi the hereinbefore mentioned auxiliary motion and a by-pass valve operable pump and motor,- and normally effective to actuate and to positively control said motor or to lock said motor against rotation in all positions of the hereinbefore mentioned auxiliary motion, said means comprising apair of normally closed passageways respectivelyefiective to conduct liquid to said motor from said pump and from said motor to said pump; and means for rendering said circuit ineffective, thereby releasing said motor from said locking action.

WALTER FERRIS. 

